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 |  | Hawking Loses Bet; Changes Mind on Black Holes
By Jane Wardell
Associated Press
posted: 06:53 am ET
16 July 2004
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LONDON (AP) -- After almost 30 years of arguing that
a black hole swallows up everything that falls into it, astrophysicist Stephen
Hawking backpedaled Thursday. In doing so, he lost one of the most famous bets
in recent scientific history.
The world-famous author of a "Brief History of Time"
said he and other scientists had gotten it wrong _ the galactic traps may in
fact allow information to escape.
"I've been thinking about this problem for the last
30 years, and I think I now have the answer to it," Hawking told the British
Broadcasting Corp.'s "Newsnight" program.
"A black hole only appears to form but later opens up
and releases information about what fell inside. So we can be sure of the past
and predict the future."
The findings, which Hawking is due to present at the
17th International Conference on General Relativity and Gravitation in Dublin,
Ireland, on July 21, could help solve the "black hole information paradox,"
which is a crucial puzzle of modern physics.
Exactly what happens in a black hole -- a region
in space where matter is compressed to such an extent that not even light can
escape from its immense gravitational pull -- has long puzzled
scientists.
Black holes occur when a massive star burns up its
nuclear fuel and gravity forces it to collapse in on itself, and the enormous
weight of the star's outer layers implodes its core. The crushing force of
gravity prohibits nearly all light from escaping and nothing inside can be
glimpsed from the outside.
The star virtually disappears from the universe into
a point of infinite density, a place where the laws of general relativity that
govern space and time break down.
Hawking has devoted most of his life to studying
these questions.
Initially, cosmologists believed the holes were like
a cosmic vacuum cleaner, sucking up everything in their path.
Hawking revolutionized the study of the holes when he
demonstrated in 1976 that, under the strange rules of quantum physics, once
black holes form they start to "evaporate" away, radiating energy and losing
mass in the process.
Under this theory, black holes are not totally
"black" because the vacuum of the imploding star lets out very tiny amounts of
matter and energy in the form of photons, neutrinos and other
subparticles.
By conjuring up this so-called "Hawking radiation,"
the Cambridge mathematician, who is paralyzed by amyotrophic lateral sclerosis,
also created one of the biggest conundrums in physics.
These particles, he said, contained no information
about what has been occurring inside the black hole, or how it formed. Under his
theory, once the black hole evaporates, all the information within would be
lost.
But now, according to his latest revision, Hawking
argues that eventually some of the information about the black hole can be
determined from what it emits.
The information has important philosophical and
practical consequences.
"We can never be sure of the past or predict the
future precisely," he said. "A lot of people wanted to believe that information
escaped from black holes but they didn't know how it could get out."
Hawking did not elaborate on the BBC program how the
information could be extracted from the black hole.
Curt Cutler, from the Albert Einstein Institute in
Golm, Germany, which is chairing the meeting in Dublin, told New Scientist
magazine that Hawking asked at the last minute for permission to address the
conference.
"He sent a note saying `I have solved the black hole
information paradox and I want to talk about it,"' Cutler said.
If Hawking succeeds in making his case, he will lose
a bet that he and theoretical physicist Kip Thorne of the California Institute
of Technology made with John Preskill, also of Caltech.
The terms of the bet were that "information swallowed
by a black hole is forever hidden and can never be
revealed."
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